For the most part the benchmarks flicker back and forth between Vista and Windows 7 with no outright winner. There are a few concerns we have at this time though - file compression tests are notably and consistently slower and network copy performance is very slightly slower as well. However, on the plus side, the simple file copy testing is faster than in Vista and boot times are notably improved.
Windows 7 is supposed to be much more lightweight, too, and we've seen it running on Atom-based machines without too much trouble. We've obviously tested here with an incredibly high-end system and so the performance differences may not be as noticeable at this end of the spectrum. Where the optimisations might make more of a telling difference is at the lower end of the scale, where hardware performance is very much the bottleneck of your experience with an operating system like Windows Vista or Windows 7.